LCDs can be used to display messages or other information. A LCD is composed of several segments, which can be visible or invisible. A segment has two electrodes with liquid crystal between them. The electrodes may be referred to, respectively, as the common terminal (COM) and the segment terminal (SEG), which is connected to a segment driver. See FIG. 1. When a voltage above a specified threshold voltage is applied across the liquid crystal, the segment becomes visible. In general, the LCD is driven by alternating current (AC), because direct current (DC) causes electrophoresis effects in the liquid crystal and can degrade the display.
Some LCD modules have built-in drivers/controllers, which handle the generation of characters or graphics on the glass plate in which the liquid crystal is contained. In other cases, a microcontroller can have a built-in LCD driver, which allows the microcontroller to drive the LCD glass directly, thereby eliminating the need for the driver to be integrated into the LCD module.
A microcontroller with a built-in LCD driver can be implemented, for example, as an integrated circuit (IC) chip that is disposed in a package. Different packages with a variety of different input/output (I/O) pin layouts are available. Terminals on the IC chip need to be electrically connected (e.g., bonded) to the package's I/O pads. However, as a result of bonding constraints, physical segment terminals cannot necessarily be used in continuous order in all packages. As shown in FIG. 2, the microcontroller chip (i.e., a die) can be mounted, for example, in either of two packages, one of which results in there being some segment terminals that are not bonded. One difficulty that can arise is that the distribution of unbonded segment terminals may differ from one chip-package combination to another chip-package combination.